Stop that Apple Going Brown!

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Objective

Students will be able to help plan and carry out an investigation that will show what is the best method to stop an apple going brown and rotting.

Big Idea

Testing different liquids on apples to prevent oxidization provides students with an opportunity to practice their investigation skills.

Introduction

15 minutes

Gather students on the rug using a preferred classroom management technique. I like to use my “Stop, look, listen.” The students stop what they are doing, look at me and listen for the direction. I usually preface the direction with, “When I say go…” This reminds the students to listen to the whole direction before moving to follow the directive.

In this case I would say, “When I say go I would like you to clear your space, push in your chair and go take a spot on your dot. Walking feet go.”

By saying “walking feet” I am reminding the students to use walking feet in the classroom to ensure safe movement between areas.

When all of the students are seated on their dot in the rug area I ask the students, “Who has ever opened up their snack and found their apple has turned brown when it used to be white?”

“I see by the show of hands that several of you have observed this. Raise your hand if you think you know why this happened.”

If any students raise their hand I select two or three of them to respond. I only select a few because I do not want to lose my audience’s attention.

“Those were all good ideas. An apple turns brown after you have cut it because of a process called oxidization. Oxidization occurs because of an enzymatic reaction. Today you are going to help me test to see if we can slow down or stop the oxidization process.”

  

I use this brief discussion to engage my students’ attention. This discussion provides the students with an opportunity to share what they have observed and what they may know about the oxidization process. 

Activity

45 minutes

“Room 203 scientists you are going to help me set up an experiment to answer the question, “Which liquid do you think will prevent the apple from turning brown the best?”

“Now that we have our question, I need to ask if anyone can tell me what a liquid is.”

“Great memory Harper; a liquid is something I can pour and it was neat that you recalled that fact from our experiment back from our hearing lesson.”

“Now I would like to ask you what would be some good liquids to test and why?”

I select several students who are following the correct classroom protocol of raising their hand to respond to the question. Responses will vary based on student knowledge and experiences.

“Okay those were all good suggestions and reasons. I happen to have lemon juice, water and milk here so those are the liquids we are going to test. I also have my apple, a knife, a pen, Post-it notes and a tray.”

“What do you think I should do now?”

I select two or three students to respond to the question.

“I like the way Nate said we should cut the apple and pour the different liquids over a piece of apple and put it on the tray. How will I remember which apple piece has which liquid on it?”

I let the students call out the response, “Label it!”

“Fantastic now I remember that from our bread bacteria experiment. What should I do next?”

I am hoping that someone will remember how we need a control. If no one recalls it I remind the students about our bread bacteria experiment again to prompt them. “There is one very important thing I need to compare my liquid covered apple pieces too. This helps me draw my conclusion of which is the best liquid to stop my apple going brown. I will give you a hint it begins with the sound /c/.”

“That’s right Bryan; I need a control. My control shows me what happens when I do not do anything and I can compare the other pieces of liquid covered apple to it. That way I can observe the difference and decide which liquid is best. Remember I am looking for which liquid prevents the apple from turning brown.”

“Okay; now that we have our liquid covered apples and our control, can I put one apple over here and one over there and one in another room?”

I allow the students to call out the response, “No!”

“Why not?”

I select a student that has their hand raised.

“Well done Max; that would not be a fair test. All of the apples have to be in the same conditions so it is a “fair test.” To be “fair” I can only change one thing and today that is the liquid I put on the apple.”

“At one of our stations today you are going to draw what our tray looks like at the beginning of our experiment so take a good look at it. I will also take a photo of it for our class records.”

Our experiment set-up.

Students working on recording our experiment

Student working on recording the experiment

Student working on experiment recording

“After handwriting this afternoon we will look at our experiment again and observe the results. Then we will make a conclusion and record it in our science journals.”

“Does anyone have any questions?”

Student shares the experiment results

 

Now I send the students over to the integrated work stations one table group at a time to maintain a safe and orderly classroom. It usually sounds like this;

“Table number one go get ready to have some recording fun.

Table number two, you know what to do.

Table number three, hope you were listening to me, and

Table number four, you shouldn’t be here anymore.”

 

Allow the students 15-18 minutes to work on this activity. After 15-18 minutes are up, the timer goes off and the students clean up ready to switch stations.  

I set the visual timer and remind the students to look at it so they can use their time wisely.

 

In this activity the students are exploring how to set up a “fair test.” 

Extensions

At another work station the students are predicting what other fruits and vegetables may oxidize when cut open. The students are asked to make a prediction and then support their prediction with a possible explanation. Once the students have made their prediction we will cut open the given fruits and vegetables to test their predictions (science). Test subjects will be: potato, tomato, banana, orange, avocado and carrot.  

Students predicting which fruit or vegetable will oxidize first

 

At another work station the students are going to test which container is the best one to store an apple in. In other words, “Which container is the best one to slow down the oxidization process and why?” Containers to be tested will be: Ziploc bag (sandwich kind not freezer), glass jar, and plastic sealable container. An apple will be the test subject used in all containers. The station leader will explain this is because we are testing the container not the fruit – we can only change one variable to make it a simple fair test (science).   

Students working on predicting which container is best to slow down oxidization

Student predicts which container will be best

 

At another work station the students will be painting with lemon juice and then we will leave the papers to dry. Later in the day during free choice center time I will have the students take turns coming over to use the iron. Running the iron over the paper burns the acid which then causes the picture to appear (science).  

Students painting with lemon juice  

 

These activities provide the students with the opportunity to apply and expand their understanding of the concepts within new contexts and situations thus elaborating on the information they have been presented with. 

Closure

15 minutes

When the time is up I blow two short blasts on my whistle and use the “Stop, look, listen” technique mentioned above.

“When I say go, I would like you to clean up your space remembering to take care of our things, push in your chair and take a spot on your dot. Walking feet, go.”

 

Once the students are seated I tell them that we are going to look at apple experiment we started earlier this morning.

“Boys and girls we are going to take a look at our apples that we placed on the shelf. Just before we do that can anyone tell me one of the liquids we are testing on our apples?”

I select a student who is following the classroom protocol of raising their hand.

“Nice recall Ashleigh; lemon juice. What is another liquid we are testing?”

Once I again I select a student who is raising their hand.

“Yes Noah; we used water. And our last liquid?”

I select another student.

“You are absolutely right Colin; milk. What about the last piece of apple?”

I select another student.

“Well done Nate; we did not do anything to that apple. Can someone tell me why?”

I select a student I know who will give me a correct response because I do not want other students to become confused.

“Fantastic Finneas; this apple is our control. Our control tells us what happens when we do not do anything. This gives us a base to compare our results too.”

“Now let’s take a look at our apples.”

I bring the tray down and we discuss what we observe. We compare each of the apple slices to the control we set up. Based on what we observe we draw our conclusions and I ask the students to come up with possible explanations.

Once the students have exhausted their ideas I explain to them, “Oxidization can be prevented or slowed down by not allowing oxygen to get to the surface of the fruit. You can do this in many ways. You can cook the food which heats up the food and stops the enzymatic reaction; you can cover the food to stop air reaching the food, which is what we tested at our container station; and finally you can alter the pH balance on the fruit surface by making it more acidic which also stops the enzymatic reaction.”

“Now that you have all seen the results and made your conclusions based on your observations, I will use the fair sticks to pick students to tell me which liquid they think is the best one to stop an apple going brown. Once you have told me which one you think is best you may use the hand sanitizer and go get your snack.”

I use the fair sticks to determine the order of the students. Dismissing the students this way means I control the flow of students from one area of the classroom to the other.     

 

I use this exit process as a way for the students to analyze what they observe and explain what the results are. During integrated work station time the students’ experienced different activities which involved the oxidization process and different ways to set up a “fair test.” Now the students can assess the results of a “fair test” and make conclusions based on their observations. 

Assessment

In order to assess if my students have successfully understood and retained the information presented in the lesson I evaluate each student by providing them with a task the next day for morning work. For this assessment I write the following question on the morning work board, “What is one way I can make a “fair test? Draw your answer.”

Because of the complexity of the question I have the students draw rather than write. Once the student has drawn what they believe a fair test may look like, I have the student bring his/her work over to me and discuss what they have drawn. I will act as a scribe and write what the student tells me directly into his/her journal as an anecdotal record.  

Journal entry for assessment 1

Journal entry for assessment 2

Student sharing his fair test journal entry

Student sharing how her test is fair